Photoacoustic imaging, which can provide the maximum intensity contrast in tissue depth imaging without ionizing radiation, will be a promising imaging trend for tumor detection. In this paper, a column diffusion fiber was employed to carry a pulsed laser for irradiating stomach directly through esophagus based on the characteristics of gastric tissue structure. A long focused ultrasonic transducer was placed outside the body to detect photoacoustic signals of gastric tissue. Phantom and in vitro experiments of submucosal gastric tumors were carried out to check the sensitivity of scanning photoacoustic tomography system, including the lateral and longitudinal resolution of the system, sensitivity of different absorption coe±cient in imaging, capability of transversal detection, and probability of longitudinal detection. The results demonstrate that our innovative technique can improve the parameters of imaging. The lateral resolution reaches 2.09 mm. Then a depth of 5.5mm with a longitudinal accuracy of 0.36mm below gastric mucosa of early gastric cancer (EGC) has been achieved. In addition, the optimal absorption coe±cient differences among absorbers of system are 3.3–3.9 times. Results indicate that our photoacoustic imaging (PAI) system, is based on a long focusing transducer, can provide a potential application for detecting submucosal EGC without obvious symptoms.

Quantification of fiber orientation is the key to characterizing the tissue mechanical properties and diagnosing diseases. A center line-based algorithm is presented for estimating the orientation distribution that first skeletonizes a binary image of fibers, followed by orientation estimation using a weight vector summation algorithm along the center line of image. Then we use the orientation at the skeleton to approximate the orientation of each pixel between the boundary and skeleton. The algorithm is applied for characterizing collagen fibers of mouse skins in second harmonic generation (SHG) image, and the circle standard deviation of orientation could be a biomarker to differentiate the naturally aging skins.

对纹理图像的分析及特征提取是近年来图像处理领域的研究热点, 在现实中有广泛的应用价值。灰度共生矩阵已被理论证明是图像纹理分析的一个很好的方法。为了使灰度共生矩阵所提取的特征值能够更好地描述皮肤老化的灰度分布信息, 以不同年龄层的女性的不同部位的皮肤纹理图像作为研究对象, 对采集到的图像进行预处理, 采用灰度共生矩阵法提取纹理的特征值, 通过统计分析得出了特征值的变化规律。实验结果对皮肤老化研究及其纹理分析有参考意义。

使用OCT技术观察活体小鼠皮肤组织在非消融性激光作用后光热损伤及其修复过程,得出皮肤组织在此过程中形态上的变化规律。利用OCT散射模型得出皮肤在激光作用前后光学参数中衰减系数的变化, 根据所获得的光学参数的变化量来判断热损伤程度, 并分析引起散射参数变化的原因,作为临床上无损的判断光热作用下皮肤内部损伤情况的依据。结果表明OCT是一种很有潜力的活体监测光热损伤及其修复过程的工具。